1. Field of the Invention
The invention relates to a method for producing a mirror from a titanium-based material having a shape accuracy and having a surface roughness in the submicrometer region by using the techniciue of ultraprecision machining.
2. Discussion of the Prior Art
A method for machining surfaces based on the material of titanium was advanced in the form of a poster presentation by Z. Tanaka et al. at the 10th World Conference on Titanium, Ti-2003, Hamburg. A reflecting surface having a flatness in the region between 700-900 nm and a surface roughness between 60-70 nm is produced with the aid of this method by ultraprecision grinding with a diamond disc on a plane surface.
Titanium-based materials are materials of great hardness that are wear-resistant and extremely insensitive to atmospheric influences. These materials count among the light metals and are therefore principally suited for mirrors in homing heads for guided missiles. However, mirrors with a plane surface do not generally exhibit the properties with reference to the optical beam path which are required in homing heads. A basic shape for a mirror in a homing head is described, for example, in EP 1 256 832 A2. It is possible by means of this basic shape to focus the radiation impinging on the mirror and to implement a prescribed beam path. Since such applications require a high image quality, radiation incident on the mirror must be reflected particularly effectively.
It is disadvantageous that only mirrors with a plane surface and no reflecting surfaces with stringent requirements placed on reflectivity can be produced from a titanium-based material using the method described in the abovenamed prior art.